说明：  用Cadence画图时，需自己设计元件封装。幸好有Mentor Graphics IPC-7351 LP Viewer 10.2，这是个基于IPC-7351通用标准的浏览软件，可以查看各种器件的封装。 IPC-7351标准覆盖所有类型的无源及有源器件件的焊盘图形设计，包括电阻器、电容器、MELFS、TSSOPS、QFPS、球形阵列封装、方形扁平无引脚封装、小外形无引线封装等。IPC-7351为每个元件提供了三个焊盘图形几何形状，即高元件密度、中等元件密度、低元件密度，软件中对应的CAD data库分别是SMM/ SMN/ SML，就是各个库中对应的相同的封装的焊盘尺寸不一样： 高元件密度SMM：焊盘最小。 中等元件密度SMN：焊盘一般。 低元件密度SML：焊盘最大情况，最牢固，如需翻修，最方便。
(When using Cadence drawing, need to design packaging. Fortunately have a Mentor Graphics IPC- 7351 LP Viewer 10.2, this is a browser software based on IPC- 7351 general standard, can see all kinds of devices of encapsulation. The IPC- 7351 standard covers all types of passive and active components of bonding pad of graphic design, including resistor, capacitor, MELFS, TSSOPS, QFPS, ball grid array, encapsulation, small square flat without pin shape leadless package, etc. IPC- 7351 for each component provides three solder graphics geometry, namely high cell density, the density of secondary element density, low element, the corresponding CAD software data library is SMM/SMN/SML, respectively is corresponding to the same in every library encapsulation of bonding pad size is not the same as: High component density SMM: solder is minimal. Secondary component density SMN: bonding pad. Low element density SML: bonding pad is biggest, the most strong, for renovation, the most convenient t)